This invention pertains to a series of new derivatives of (2-azinylamino) quinone, their synthesis, and the use of these derivatives as 5-lipoxygnease inhibitors.
Leukotrienes, identified as 5-lipoxygenase (5-LO) metabolites of arachidonic acid (AA), have been implicated as mediators in a diversity of diseases, including asthma and a number of other inflammatory pathologies, such as rheumatoid arthritis, inflammatory bowel disease, psoriasis and glomerulonephritis. See S. W. Crooks et al., xe2x80x9cMolecules in focus: Leukotriene B4,xe2x80x9d The Internat. J. Biochem. and Cell Biol., vol. 30, pp. 173-178 (1998). Although leukotrienes may not be involved in the initial stages of a disease, they appear to play an important role in the propagation of the disease, by exacerbating the initial, primarily local events and eventually leading to tissue damage.
Through the action of 5-LO, AA is initially oxygenated to give 5-hydroperoxyeicosatetraenoic acid (5-HPETE), which is then transformed by the same enzyme to leukotriene A4 (LTA4). LTA4 is then converted by LTA4-hydrolase to leukotriene B4 (xe2x80x9cLTB4xe2x80x9d), a potent chemotactic agent that enhances infiltration of leukocytes and their subsequent degranulation. See Crooks et al., 1998. Alternatively, LTA4 can couple to glutathione to produce peptidoleukotrienes (PLTs) LTC4, LTD4 and LTE4 that have profound effects on bronchial and vascular smooth muscle contractility, and promote extensive plasma extravascularization by increasing the permeability of the postcapillary venules. See, e.g., S. P. O""Hickey et al., xe2x80x9cLeukotrienes C4, D4, and E4 enhance histamine responsiveness in asthmatic airways,xe2x80x9d Am. Rev. Resp. Dis., vol. 144, pp. 1053-1057 (1991).
Since the elucidation of the 5-LO biosynthetic pathway, an ongoing debate in drug development has been whether inhibition of the 5-LO enzyme is more efficacious than antagonization of the peptido- or non-peptido-leukotriene receptors. However, evidence suggests that 5-LO inhibitors may be superior to LT-receptor antagonists, since 5-LO inhibitors block the action of the full spectrum of 5-LO products, whereas LT-antagonists produce narrower effects. See D. G. Redkar-Brown et al., xe2x80x9cInhibition of antigen-induced contraction of guinea pig trachea by ICI 198,615,xe2x80x9d Eur. J. Pharmacol. vol. 165, pp. 113-121 (1989); and T. R. Jones et al., xe2x80x9cAntigen-induced contraction of guinea-pig isolated trachea: Studies with novel inhibitors and antagonists of arachidonic acid metabolites,xe2x80x9d Br. J. Pharmacol., vol. 95, pp. 309-321 (1988). In addition, LT-receptor antagonists appear to prolong the half-lives of LTs by hindering their metabolism. See C. Denzlinger et al., xe2x80x9cEffect of leukotriene receptor antagonists on leukotriene elimination in the rat,xe2x80x9d Allergy Clin. Immunol., vol. 85, pp. 218 (1990).
Numerous attempts have been made in the last decade to identify and develop 5-lipoxygenase (5-LO) inhibitors as therapeutic agents. Among the compounds include several having a 1,4(or 1,2)-quinone moiety. The p-benzoquinone derivative 1 and the o-naphthoquinone 2, with structures as shown below, have been revealed as potent inhibitors of 5-LO. See S. Terao et al., xe2x80x9cQuinones. Part 2. General Synthetic Routes to Quinone Derivatives with Modified Polyprenyl Side Chains and the Inhibitory Effects of these Quinones on the Generation of the Slow Reacting Substance of Anaphylaxis (SRS-A),xe2x80x9d J. Chem. Soc. Perkin Trans., vol. 1, pp. 2909-2920 (1982); A. Rakhit et al., xe2x80x9cPharmacokinetic Screening of o-Naphtoquinone 5-Lipoxygenase Inhibitors,xe2x80x9d Pharm. Res., vol. 7, pp. 1071-1076 (1990); S. Ohkawa et al., xe2x80x9cDual Inhibition of Thromboxane A2 Synthetase and 5-Lipoxygenase with Scavenging Activity of Active Oxygen Species. Synthesis of a Novel Series of (3-Pyridylmethyl)benzoquinone Derivatives,xe2x80x9d J. Med. Chem., vol. 34, pp. 267-276, (1991). See also, U.S. Pat. Nos. 4,393,075; 4,851,415; 4,985,447; and 5,106,858; and of International Application WO 86/04058. The series of(3-pyridylmethyl)benzoquinone derivatives were evaluated for inhibition of thromboxane A2 (TXA2) synthase, inhibition of 5-LO, and scavenging activity of active oxygen species (AOS), and the compound with the structure 3 shown below was the most promising derivative. (Ohkawa et al., 1991). 
We have synthesized a series of new derivatives of (2-azinylamino)-quinone, structure 4 as shown above. All (2-azinylamino)quinones are antioxidants. Several compounds of this new series of derivatives have been shown to be inhibitors of 5-lipoxygenase, with minimal or no effect on cycloxygenase-1 and 2-(COX-1 and COX-2) activity.
The series of new compounds have the following General Formula 4: 
where:
A is N, CH, or CCl;
B is N, CH, CCH3, or CPh;
X is,H, Cl, Br, or I;
Y is H or CH3;
R1 is H, CH3, OCH3, or Ph; and R2 is H, CH3, OCH3, or Ph; or R1xe2x80x94R2 is (CHxe2x95x90CH)2; and
R3 is H or CH3.
Note that in the above formula when R1xe2x80x94R2 is (CHxe2x95x90CH)2, this forms a naphthoquinone having a structure as exemplified below: 
The compounds of General Formula 4 can be used as medication to be administered orally, rectally, topically, parenterally or inhalation, in the form of a pharmaceutical preparation, which contains at least one of the compounds of General Formula 4 in combination with a pharmaceutically acceptable carrier. The pharmaceutical carrier is selected with regard to the intended route of administration and standard pharmaceutical practice. For example, the compounds may be administered orally in the form of tablets containing such excipients as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs or suspensions containing flavoring or coloring agents. They may be injected parenterally, for example, intravenously, intramuscularly, or subcutaneously. For parenteral administration, they are best used in the form of a sterile aqueous solution which may contain other substances, for example, salts or glucose. The amount of active compound is between 0.1 and 99% by weight of the preparation, preferably between 2 and 50% by weight in oral preparations. The daily dose of the active substance depends on the type of administration and, in general, is between 25 and 100 mg if administered orally and between 0.1 and 50 mg per dose if administered intravenously. In clinical practice, the dosage will be adjusted for the particular patient and may vary with age, weight, and response of the patient. The above dosages are exemplary of an average case but can be increased or lowered if merited.
The preparation of the compounds of General Formula 4 is further illustrated by the following examples. In general the compounds were synthesized as shown below by reaction between the aminides 5 and the corresponding quinones 6 to yield the aminoquinones 4a-y (Table 1). The aminides 5a-e were prepared from the corresponding pyridinium salts as previously described. See R. Carceller et al., xe2x80x9cPyridinium-N-(2-pyridyl)aminides: A Selective Approach to Substituted 2-Aminopyridines,xe2x80x9d Tetrahedron Lett., vol. 34, pp. 2019-2020 (1993); R. Carceller et al., xe2x80x9cAzinium-N-(2xe2x80x2-azinyl)aminides: Synthesis, Structure and Reactivity,xe2x80x9d Tetrahedron, vol. 50, pp. 4995-5012 (1994); and C. Burgos et al., xe2x80x9cHalogenation of Pyridinium-N-(2xe2x80x2-pyridyl)aminide. An Easy Synthesis of Halo-2-aminopyridines,xe2x80x9d Tetrahedron, vol. 51, pp. 8649-8654 (1995). Reaction of these compounds with the corresponding N-halosuccinimide in the reported conditions yielded the haloaminides 5f-i. See C. Burgos et al., 1995. The reaction between the aminides 5 and the quinones 6 was performed using silica as acid catalyst in acetonitrile. The process was accomplished at room temperature for 25-50 h. 
In compounds 4b, 4c and 4f (defined as in Table 1), heating the reaction mixture that was absorbed on silica under reduced pressure (xcx9c0.2 atm) at 30xc2x0 C. improved the yields with a decrease in reaction times (5-10 min). The synthesis of 4n was only possible, even though in low yield, under microwave irradiation. As it can be seen in the proposed mechanism above, the aminide is acting as nucleophile toward the quinone through a Michael addition. The initially formed adduct eliminated pyridine and yielded the monosubstituted quinone. See T. Sasaki et al., xe2x80x9cNucleophilic Reactions of N-ethoxycabonyliminopyridinium Ylide with xcex1,xcex2-Unsaturated Carbonyl Compounds,xe2x80x9d Tetrahedron, vol. 28, pp. 1469-1476 (1972). When 2-methyl-1,4-benzoquinone 6b was used as starting material, a mixture of the two possible regioisomers was obtained in all cases (4b and 4c, 4o and 4p, 4v and 4x). On the contrary, compound 4f was the only regioisomer isolated in the reaction of 2-phenyl-1,4-benzoquinone 6e and N-(pyridin-2-yl)pyridinium aminide 5a, probably due to both the steric hindrance and the electronic effects produced by the phenyl substituent.
After synthesis, melting points of the new derivatives were recorded on an Electrothermal IA6304 and are reported uncorrected. 1H NMR spectra were obtained on a Varian Unity 300 spectrometer at 300 MHz. IR spectra were recorded on a Perkin Elmer 1310 spectrophotometer using KBr pellets. Mass spectra were determined on a Hewlett-Packard 5988A (70 eV). Flash chromatography was carried out using Merck Kieselgel 60 (230-400 mesh), which also was used to perform solid-supported reactions. Solvents and reagents were available commercially (e.g., Sigma-Aldrich, Inc.), and were purified by standard procedures. 2-Hydrazinoazines were prepared according to known procedures. See K. Shirakawa et al., xe2x80x9cChemotherapeutics XXXIV. Syntheses of some Heterocyclic Hidrazine Compounds and their 9xc2xa7 Action on Tubercle Bacilli,xe2x80x9d J. Pharm. Soc. Japan, vol. 73, pp. 598-601 (1953); P. J. Nelson et al., xe2x80x9c1,2,4-Triazoles, VI. Synthesis of some s-Triazolo[4,3-a]pyrazines,xe2x80x9d J. Org. Chem., vol. 27, pp. 3243-3248 (1962); J. Chesterfield et al., xe2x80x9cPyrimidines. VIII. Halo- and Hidrazinopyrimidines,xe2x80x9d J. Chem. Soc., vol. 1955, pp. 3478-3481 (1955); and M. P. V. Boarland et al., xe2x80x9cPyrimidines. IV. Experiments on the Synthesis of Pyrimidine and 4,6-Dimethylpyrimidine,xe2x80x9d J. Chem. Soc., vol 1952, pp. 4691-4695 (1952). Pyridinium salts and aminides were obtained as reported. See R. Carceller et al., xe2x80x9cAzinium-N-(2xe2x80x2-azinyl)aminides: Synthesis, Structure and Reactivity,xe2x80x9d Tetrahedron, vol. 50, pp. 4995-5012(1994); and C. Burgos et al., xe2x80x9cHalogenation of Pyridinium-N-(2xe2x80x2-pyridyl)aminide. An Easy Synthesis of Halo-2-aminopyridines,xe2x80x9d Tetrahedron, vol 51, pp. 8649-8654 (1995).
Generalprocedure A. Into a mixture of N-(azin-2-yl)pyridinium aminide (2.0 mmol), the corresponding xcex1,xcex2-unsaturated carbonyl derivative (2.0 mmol) and silica gel (2.0 g) in dry acetonitrile (10 mL) were stirred at room temperature for the period indicated below. The silica was removed by filtration, the solvent evaporated, and the residue was purified by flash chromatography and recrystallized if necessary.
General procedure B. N-(azin-2-yl)pyridinium aminide (2.0 mmol), the corresponding xcex1,xcex2-unsaturated carbonyl derivative (2.0 mmol) and silica gel (2.0 g) in dry acetonitrile (10 mL) were stirred, the solvent evaporated to dryness in vacuo (xcx9c0.2 atm) heating at 30xc2x0 C., and the residue was purified by flash chromatography and recrystallized if necessary.